Earthquake-strengthening work on the Karori Tunnel is several weeks behind schedule, but contractors are confident it will be completed by the end of the year.
An assessment by Wellington City Council last year revealed the tunnel was unlikely to withstand an earthquake greater than magnitude 7.
Work began in February and includes securing the tunnel to the hillside, reinforcing the concrete buttresses and building a concrete retaining wall on the hillside by the city-side entrance.
Karori tunnel project manager Faiz Tawfeek said work was behind schedule, but extra workers were being hired to get back on track. The work should still be finished by the end of the year.
"On the Karori side, we are putting in 14 new rock anchors.
"About 70 per cent of these are now in place," he said.
"On the city side, we have made a start on the new sprayed- concrete retaining wall.
"We are also about to put up more scaffolding on the city side so that we can install 21 rock anchors to secure the tunnel entrance."
The tunnel is down to one lane from 9.30am till 3pm and 7pm till 11pm, Monday to Friday, and on Saturday from 7am till 9am.
- The Wellingtonian